Flexible printed circuit boards are increasingly being used in high density, small electronic components. Such circuit boards are typically produced from a “copper clad laminate” that contains a copper foil and an insulating film. However, the laminate often curls during heat treatment due to the relatively poor heat resistance of the polymers used to form the film. In this regard, liquid crystalline polyesters have been suggested for use in forming the insulating film due to their relatively high degree of heat resistance. Nevertheless, one of the problems in successfully incorporating these types of polymers into flexible printed circuit boards is that they are not soluble in most solvents, and thus cannot be readily cast into a film. Various attempts have been made to solve this problem. For example, one liquid crystalline polyester that has been proposed for producing films is formed from 2-hydroxy-6-naphthoic acid (“HNA”), 2,6-naphthanlenedicarboxylic acid (“NDA”), and 4,4′-dihydroxydiphenyl ether. While allegedly having improved solubility, the polyester requires a very high amount of naphthenic monomers to achieve sufficient liquid crystallinity and mechanical strength. Unfortunately, the high cost of naphthenic acid monomers dictates that the need for others solutions to the problems noted.
As such, a need exists for a polymer that contains a low naphthenic content, but yet is still capable of possessing a sufficient degree of solubility in various solvents to that it can be readily formed into a film.